Semiorganic nonlinear optical l-lysine sulphate growth and characterization

l-Lysine sulphate (LLS), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30–50 °C. Single crystals have been grown by slow evaporation method from an aqueous acetone solution of l-lysine and sulphuric acid. The grown crystals were bulk, bright and transparent. These crystals were characterized by X-ray and FTIR studies. Powder X-ray pattern indicates that LLS crystallizes in orthorhombic space group P2₁2₁2₁ with four unit cells. FTIR spectral studies were performed for the conformation of the l-lysine molecule and hydrogen bonds. The optical transmission spectra of the grown crystal are tested by UV–vis spectrophotometer and found that the crystal was transparent over entire visible region. The second harmonic generation test of the LLS revealed the nonlinear nature of the crystal.